CVE-2026-28390: Possible NULL Dereference When Processing CMS KeyTransportRecipientInfo

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-07 · updated 2026-07-24
Weakness: CWE-476

Description

Issue summary: During processing of a crafted CMS EnvelopedData message with KeyTransportRecipientInfo a NULL pointer dereference can happen. Impact summary: Applications that process attacker-controlled CMS data may crash before authentication or cryptographic operations occur resulting in Denial of Service. When a CMS EnvelopedData message that uses KeyTransportRecipientInfo with RSA-OAEP encryption is processed, the optional parameters field of RSA-OAEP SourceFunc algorithm identifier is examined without checking for its presence. This results in a NULL pointer dereference if the field is missing. Applications and services that call CMS_decrypt() on untrusted input (e.g., S/MIME processing or CMS-based protocols) are vulnerable. The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.

Affected products

OpenSSL: from 1.0.2 before 1.0.2zp; from 1.1.1 before 1.1.1zg; from 3.0.0 before 3.0.20; from 3.3.0 before 3.3.7; from 3.4.0 before 3.4.5; from 3.5.0 before 3.5.6 — fixed in 1.0.2zp, 1.1.1zg, 3.0.20, 3.3.7, 3.4.5, 3.5.6

How to fix

Upgrade to a fixed version: OpenSSL 1.0.2zp, 1.1.1zg, 3.0.20, 3.3.7. Check the vendor advisory for mitigations.

References

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